The primary objective of the experiments outlined in the initial proposal was to obtain information on the central representation of the modalities associated with small diameter fibers, especially those projections related to cutaneous pain and temperature. Systematic stimulus-response data will be collected from temperature sensitive neurons in the spinal cord and thalamus of primates in order to assess the specificity and transformation of small afferent fiber projections. The locations of the isolated neurons will be correlated with concurrent anatomical studies of the origin and terminal projections of the spinothalamic system.